It is known to weigh the amount of load (e.g., passenger weights) within an elevator car and to generate a first electrical signal when a fixed percentage of full elevator car capacity is equalled or exceeded. The electrical signal is transmitted to or generated within an electronic car controller (e.g., electronic computer) for the elevator car to cause the car controller to command a particular elevator car to bypass hall calls. When the load within the particular elevator car decreases to a value below the fixed percentage (e.g., because passengers exit the car at a landing), a second electrical signal is transmitted to or generated within the car controller to command the car to answer appropriate hall calls. Typically, full capacity of an elevator car is 4,000 pounds and the fixed percentage is 80%. Values corresponding to the 4,000 pounds and to the 80% are conventionally stored, for example, in a computer memory of the controller. Usually, the controller receives a load weight signal (LW) corresponding to an actual load from load weight sensors disposed within the elevator car, calculates an actual percentage of full capacity, compares the actual percentage against the fixed percentage, and generates the first electrical signal to cause the controller to inhibit the car's response to hall calls while the fixed percentage is equalled or exceeded. The fixed percentage is known in the art as the load weight bypass threshold. The first electrical signal is commonly termed a load weight bypass threshold signal. Arrangements for generating the load weight bypass threshold signal responsive to a load weight signal LW are well known and commercially used in the art. Such arrangements exist, for example, in the ELEVONIC 411 elevator system manufactured and sold by the Otis Elevator Company.
It is also known to adjust the load weight bypass threshold to a low value during light traffic conditions and to a higher value during heavy traffic conditions so that the waiting time of passengers at floors can be reduced by having an elevator car that has reached its load limit bypass floors. See, for example, U.S. Pat. No. 4,708,224, "Apparatus for the Load Dependent Control of an Elevator," issued Nov. 24, 1987 by Joris Schrooder, and U.S. Pat. No. 3,504,770, "Elevator Supervisory System," issued Apr. 3, 1970, by H. C. Savino et al.
Nevertheless, the present inventors believe that improvements in arrangements and methods for adjusting load weight bypass thresholds are achievable.
In order to increase group elevator performance, an elevator car should stop for a hall call when there is ample or sufficiently available space (e.g., floor space) in the elevator car for the waiting passengers and should bypass the hall call when there is not ample space. A situation often encountered in buildings such as hotels or hospitals, etc. is that guests, porters, attendants and/or patients often carry luggage or the like onto the elevator car. Thus, the available floor space in the elevator car frequently will be filled, but not filled with sufficient load weight to activate the load weight bypass feature--i.e., to generate the load weight bypass threshold signal. Thus, an elevator car having insufficient available space will stop for a hall call but the waiting passengers will be unable to board and must re-enter a hall call.